1. Field
The present invention relates to pin sockets and, more particularly, to zero force insertion and extraction pin sockets.
2. Background Information
Current integrated circuit (IC) package configurations include a large number of pins by which electrical signals are transmitted to and from the circuits in the package. Pins are typically constructed of thin strips of copper, gold, or other electrical conductors which protrude from the IC package and which are typically connected to other, external circuits using solder joints. As ICs increase in complexity, the number of pins comprised by IC packages also increases. A collection of package pins is sometimes called a pin grid array (PGA).
IC packages are often coupled to circuits external to the IC using sockets. Sockets are mechanical couplers that are typically soldered directly in external circuits and which provide an electrical connection to the external circuit for IC packages which are inserted into the sockets. Sockets offer advantages over direct solder connections between ICs and the external circuits. For example, an IC package which is mounted in a socket can be installed and removed numerous times from the external circuit without soldering and unsoldering the package pins.
As the number of pins comprised by IC packages increases, it typically becomes more difficult to insert and remove the package pins from an associated socket because of the resistance encountered by the pins as they descent into the socket. Each pin may make electrical contact with a conductor in an associated socket pin receiver, the conductor in electrical contact with the external circuit. Electrical coupling between package pin and socket pin receiver conductor is typically accomplished through contact between the conductor in the socket receiver and the inserted pin. While the insertion and extraction resistance associated with contact to a single package pin is not substantial, for packages with large PGAs (sometimes on the order of hundreds of pins) the accumulated resistance may become an impediment to easy insertion and removal of the package pins into and out of the socket. The accumulated force may be so substantial that insertion of the package pins into the socket may result in damage to the package pins.
FIG. 1 shows an embodiment of a prior art socket 100 to alleviate resistance to insertion and removal of a pin 160 into a well 170 in a socket body 110. Sockets for this purpose are typically called zero insertion force (ZIF) sockets. Before the pin 160 descends into the well 170, a normal force Fx is applied to the head of an electrically conductive element 150. The normal force Fx is typically applied using a member 120 coupled to a mechanical cam/lever assembly (not shown). The normal force Fx causes the element 150 to flex in a manner which provides the descending pin 160 an unobstructed path down into the well 170. This unobstructed path reduces the amount of downward force Fz to be applied to insert the pin 160 to nearly zero. Once the pin 160 is inserted in the well 170, the lever is operated to return the member 120 to a position that returns element 150 to a position in which it makes electrical contact with the pin 160. In this position the element 150 exerts a normal force against the pin 160 to retain the pin 160 in the well 170 and create an electrical connection. The element 150 may descend through a bottom 130 of the socket body 110 and terminate in an end 140 which is capable of being soldered to an external circuit.
Several disadvantages are associated with the prior art socket embodiment shown in FIG. 1. The socket may be complex and relatively costly to manufacture because of the additional parts and connections employed by the cam/lever action to flex the element 150. It is typically difficult, for example, to manufacture such sockets as single-piece units. More parts require more material and commensurate more weight and expense. Because a lever action is used, clamping a pin may employ as many as three distinct motionsxe2x80x94actuation of the lever to flex the element 150, insertion of the pin 160 and reverse actuation of the lever to unflex the element 150. Furthermore, variation of the normal force applied by the element 150 against the pin 160 cannot easily be accomplished without redesigning the shape and position of the element 150 and/or the dimensions of the well 170.
A socket includes an electrically conductive element situated within a well. The element is situated such that a first end of the element extends above a first surface of the socket. The element is capable of flexing to exert a force on a pin inserted into the well upon application of a force to the first end of the element by a descending surface.